Cave insects

Cave dwelling insects are among the most widespread and prominent troglofauna (cave-dwelling animals), including troglobites, troglophiles, and trogloxenes. As a category of ecological adaptations, such insects are significant in many senses, ecological, evolutionary, and physiological.

A cave is an unusually well-defined ecological habitat in terms of its nature, time and place. Accordingly, it is not surprising that A number of insects that permanently inhabit caves, especially at the deepest levels, and are markedly specialised for niches in some of the extreme conditions. These are the true cavernicole species; troglobites rather than troglophiles or trogloxenes.

Cavernicolous insect species rarely are adapted to move from cave to cave, so they each species or community generally will be restricted wholly to certain caves or cave systems each, and commonly will have evolved in their respective home cave systems. Exceptions commonly are those that have been carried by mobile vertebrate trogloxenes or troglophiles, though in some cases a number of populations may have evolved from a single mobile troglophile population. Caves tend to be geologically short-lived, so most of the specialised adaptations are correspondingly young in evolutionary terms and to have arisen rapidly and in parallel from similar ancestors that began as similar troglophiles in separated caves. Many insect troglobites are Orthopteran, Collembolan or Blattodean, for example and given the nature of their open-air ancestral species, it would be in no way surprising that where a cave becomes available, it soon is invaded by opportunistic troglophiles that may be widely distributed and may evolve similarly in separate caves in different areas.

Caves also appear to have become the last refugium for many ancient types of insects, which are no longer found free in the open in surrounding regions. Such cave fauna thus represent, at least in part, relicts. It does not follow that they had been in those particular caves since ancient times though. For example, modern troglobitic Onychophora obviously had not been occupying their current caves since the Carboniferous period, but had entered new caves comparatively recently and flourished by exaptation.

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